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JEE Main & Advanced Physics Photo Electric Effect, X- Rays & Matter Waves Question Bank Self Evaluation Test - Dual Nature of Radiation and Matter

  • question_answer
    The surface of a metal is illuminated with the light of 400 nm. The kinetic energy of the ejected photoelectrons was found to be 1.68 eV. The work function of the metal is: \[\left( hc=1240eV.nm \right)\]

    A) 1.41 eV

    B) 1.51 eV

    C) 1.68 eV

    D) 3.09 eV

    Correct Answer: A

    Solution :

    [a] \[\lambda =400nm,hc=1240eV.nm,K.E.=1.68eV\] We know that, \[\frac{hc}{\lambda }-W=K.E.\Rightarrow W=\frac{hc}{\lambda }-K.E\] \[\Rightarrow W=\frac{1240}{400}-1.68=3.1-1.68=1.42eV\]


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